Relay



Dec. 2, 1941. R. c. BERGVALL 2,265,023

RELAY Filed March 31, 1939 IiC50ur-ce.

INVENTOR 1 ATTORNEY Patented Dec. 2, 1941 UNITED STATES PATENT OFFICE Penny Application March 31, 1939, Serial No. 265,197

2Clainis.

This invention relates to electrical contact devices and it has particular relation to time delay ays.

Most of the time delay relays heretofore available have required moving or rotating solid parts. Such parts introduce bearing problems which are objectionable as well known to the art. In some cases, a time delay is provided by means of a dashpot arrangement in which a fluid, such as air, is permitted to pass through a small opening, the rate of escape'of the fluid determining the time delay. Variations in the orifice controlling the escape of fluid make the time duration in such instruments uncertain.

In accordance with my invention, a stator is provided for producing a rotating electrical field. In this fleld an electro-conductive fluid body, such as mercury, is positioned in a suitable container. Under the influence of the rotating field, the fluid also rotates and as it rotates its surface configuration changes under the influence of centrifugal forces. By positioning electrodes to engage and disengage the surface as it changes, a time delay for the engagement and disengagement of'the electrodes is provided which is dependent upon the rate of change of the configuration of the fluid surface, A further control for the time delay may be provided by including a field reversing switch or control element for determining the direction of rotation of the electrical fleld. By so shaping the container for the fluid that the resistance to rotation of the fluid in one direction is diil'erent from the resistance to rotation of the fluid in the opposite direction, or by introducing an additional control element for th s purpose, the time delay for one direction of rotation of the fluid will be different from the time delay for the opposite direction of rotation thereof.

Accordingly, it is an object of my invention to provide an electrical contact device which requires substantially no solid moving parts.

It is a further object of my invention to provide a time delay contact device controlled by the change in configuration-of a fluid body.

It is a further object of my invention to provide a time delay device operable in either of two directions, wherein the time delays for the two directions are diflerent.

Other objects of my invention will be apparent from the following description, taken in conjunction with the accompanyin drawing, in which the single figure shows an elevational view in cross-section of a contact device embodying my invention.

Referring to the drawing, the contact device includes a housing I in which a container 2 is mounted in any suitable manner. The container holds a quantity 3 of any suitable electro-conductive fluid, such as mercury.

In order to control the movements of the fluid body 3, a rotating fleld is produced within the container 2 by any suitable means. Some of the devices suitable for this purpose include a polyphase, split phase or shaded pole stator, such as commonly employed for induction motors. In

the specific embodiment herein illustrated and described, a split phase stator l is employed for this purpose. The main phase winding of this stator is connected to a pair of terminals 5 which are mounted on an insulating panel 6 attached to the housing. These terminals 5 in turn are connected through a suitable control unit 1 to a source of alternating current 8. The split phase winding is connected to a second pair of terminals 9, which also are connected to the control unit I through a reversing switch in.

When the control unit 1 is actuated to connect the stator l to the alternating-current source 8, a rotating field is set up within the container 2. Through an induction action, this rotating fleld causes the fluid 3 to rotate, and as the fluid rotates, its surface configuration changes under the influence of centrifugal forces to a shape H represented by the dotted lines on the drawing. This change in surface configuration is employed for controlling the engagement and disengagement of a plurality of break contacts I 2, i3 and a plurality of make contacts M, ii.

It will be noted that the break contacts l2, II

For making desired contacts at predetermined.

intervals after the energization of the contact device, the make contacts i4 and IS are positioned at difierent distances above the surface of the fluid when the fluid is at rest, and adjacent the periphery of the fluid. By reference to the drawing. it will be clear that as the fluid accel-' crates subment to energization of the device,

theiluidiimeuassesthecoatactilmdlubuing maintained The structure of the container 2 may vary considerably. Although any material may be employed which is not affected by the electroconductive fluid, I prefer a non-conductive material, such as glass. Electrodes l2 to IE may be mounted on this container in any suitable manner. The electrodes i2 to I5 may be passed through openings in the upper wall of the container 2 or they may be sealed to the container as well known in the art. If the container 2 is completely sealed it may be evacuated or gases may be introduced at any desired pressure for optimum circuit interruption'performance. Instead of the common contact It being positioned at the base of the container, a contact positioned at any other position may be employed providing it maintains continuous contact with the fluid. In the position of the contact l6 illustrated, the contact would, of course, be sealed to the container 2 in order to preventloss of fluid. The shape of the container may vary appreciably, but preferably a cylindrical container is employed having a cylindrical wall 2a. Although the container 2 may have an open upper wall for some uses, the container preferably will be substantially closed.

The direction of rotation of the fluid body 3 is dependent upon the position of the reversing switch I0. By so shaping the container 2 or by employing some additional device, the resistance offered to the rotation of the fluid may be made asymmetric relative to the two directions of rotation thereof. In the specific embodiment illustrated, a plurality of spaced vanes I1 are positioned within the fluid .in the container and are mounted for rotation about a shaft lB,-here represented as a machine screw. The shaft l8 may be carried on a boss I9 which is attached to the container in any suitable way, as by a machine screw 20, a suitable liquid-tight seal bebetween the boss l9 and the. container. Movement of the vanes i1 is controlled by a ratchet 2i attached to the boss is and a pawl 22, which is carried by the vane structure and which may be spring biased against the ratchet 2|. The vanes l1 may be constructed of magnetic, conductive or non-conductive material which is not affected by the fluid 3 in accordance with the particular effects desired.

It is believed that the operation of the contact device herein described is apparent from the foregoing description. The control unit I may be operated by hand or it may be made responsive to any variable quantity, such as temperature, voltage, current or power, for connecting the contact device to the alternating-current source 8. When a connection has been established through the control unit I, a rotating field is set up within the container 2 which accelerates the fluid 3. As the fluid accelerates, the surface configuration thereof gradually changes from a plane to the configuration H shown in dotted lines. During this gradual change in the surface configuration, the circuits between the break contacts I2 and I3 and the common con tact l6 are successively broken, and the circuits between the make contacts l5 and H and the common contact iii are successively established.

iii]

When the energization of the contact device is interrupted, as by opening of the contact unit 1, the make'and break contacts are restored in re verseorder to their initial conditions.

It the energization of the contact device is such that the fluid 3 tends to rotate in a clockwise direction, as viewed fromthe top, the vanes I! offer substantially little resistance to the rotation of the fluid, and the make and break contacts are engaged or disengaged at predetermined intervals after such energization. -If the position of the reversing switch l0, however, is such that the fluid 3 tends to rotate in a counter-clockwise direction, the pawl 22 tends to hold the vanes ll stationary, and these stationary vanes resist the movement of the fluid 3. Consequently the fluid will now require a different time interval for engaging and disengaging the various make and break contacts. The position of the reversing switch. it may be determined by hand or automatically in response to any variable quantity, such as temperature, voltage, current or power, as well known in the art.

The various contacts 12 to 16 may be connected for controlling any circuit known to the art. Various contact arrangements and different numbers of contacts may be employed as desired. Since the level of the fluid 3 depends on the degree of energization of the stator I, by position ing a number of contacts, such as I4 and It, at different levels in the container, the number of contacts engaged by the fluid will be a measure of the energization of the stator 4, or a measure of the magnitude of the voltage applied to the stator.

Although I have described my invention with certain specific embodiments thereof, it is obvious that numerous modifications are possible. Therefore, I do not wish my invention to be modifled except as requested by the appended claims when interpreted in view of the prior art.

I claim as my invention:

1. In an electrical contact device, a container, mercury in said container, a plurality of contact elements extending into said container and insulated from each other, said contact elements being positioned to engage and disengage said mercury in accordance with the level of said mercury, and means for producing a rotating ,electrical field in said container for rotating the mercury contained therein, whereby said mercury under the influence of centrifugal action changes its position relative to said contact elements.

2. In an electrical contacttdevice, a container, mercury in said container, a plurality of contact elements extending into said container and insulated from each other, said contact elements being positioned to engage and disengage said mercury in accordance with the' level of said mercury, means for producing a rotating electrical field in said container for rotating the mercury contained therein in either of two directions whereby said mercury under the influence of centrifugal action changesdts position relative to said contact elements, and asymmetric means for varying the rate of change in the-flow of said mercury in accordancewith' the direction of rotation of said mercury.

ROYAL C. BERGVALL. 

